1 | /* $NetBSD: bufq_disksort.c,v 1.13 2016/11/16 10:42:14 pgoyette Exp $ */ |
2 | /* NetBSD: subr_disk.c,v 1.61 2004/09/25 03:30:44 thorpej Exp */ |
3 | |
4 | /*- |
5 | * Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc. |
6 | * All rights reserved. |
7 | * |
8 | * This code is derived from software contributed to The NetBSD Foundation |
9 | * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, |
10 | * NASA Ames Research Center. |
11 | * |
12 | * Redistribution and use in source and binary forms, with or without |
13 | * modification, are permitted provided that the following conditions |
14 | * are met: |
15 | * 1. Redistributions of source code must retain the above copyright |
16 | * notice, this list of conditions and the following disclaimer. |
17 | * 2. Redistributions in binary form must reproduce the above copyright |
18 | * notice, this list of conditions and the following disclaimer in the |
19 | * documentation and/or other materials provided with the distribution. |
20 | * |
21 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
23 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
24 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
25 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
31 | * POSSIBILITY OF SUCH DAMAGE. |
32 | */ |
33 | |
34 | /* |
35 | * Copyright (c) 1982, 1986, 1988, 1993 |
36 | * The Regents of the University of California. All rights reserved. |
37 | * (c) UNIX System Laboratories, Inc. |
38 | * All or some portions of this file are derived from material licensed |
39 | * to the University of California by American Telephone and Telegraph |
40 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
41 | * the permission of UNIX System Laboratories, Inc. |
42 | * |
43 | * Redistribution and use in source and binary forms, with or without |
44 | * modification, are permitted provided that the following conditions |
45 | * are met: |
46 | * 1. Redistributions of source code must retain the above copyright |
47 | * notice, this list of conditions and the following disclaimer. |
48 | * 2. Redistributions in binary form must reproduce the above copyright |
49 | * notice, this list of conditions and the following disclaimer in the |
50 | * documentation and/or other materials provided with the distribution. |
51 | * 3. Neither the name of the University nor the names of its contributors |
52 | * may be used to endorse or promote products derived from this software |
53 | * without specific prior written permission. |
54 | * |
55 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
56 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
57 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
58 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
59 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
60 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
61 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
62 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
63 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
64 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
65 | * SUCH DAMAGE. |
66 | * |
67 | * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94 |
68 | */ |
69 | |
70 | #include <sys/cdefs.h> |
71 | __KERNEL_RCSID(0, "$NetBSD: bufq_disksort.c,v 1.13 2016/11/16 10:42:14 pgoyette Exp $" ); |
72 | |
73 | #include <sys/param.h> |
74 | #include <sys/systm.h> |
75 | #include <sys/buf.h> |
76 | #include <sys/bufq.h> |
77 | #include <sys/bufq_impl.h> |
78 | #include <sys/kmem.h> |
79 | #include <sys/module.h> |
80 | |
81 | /* |
82 | * Seek sort for disks. |
83 | * |
84 | * There are actually two queues, sorted in ascendening order. The first |
85 | * queue holds those requests which are positioned after the current block; |
86 | * the second holds requests which came in after their position was passed. |
87 | * Thus we implement a one-way scan, retracting after reaching the end of |
88 | * the drive to the first request on the second queue, at which time it |
89 | * becomes the first queue. |
90 | * |
91 | * A one-way scan is natural because of the way UNIX read-ahead blocks are |
92 | * allocated. |
93 | */ |
94 | |
95 | struct bufq_disksort { |
96 | TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ |
97 | }; |
98 | |
99 | static void bufq_disksort_init(struct bufq_state *); |
100 | static void bufq_disksort_put(struct bufq_state *, struct buf *); |
101 | static struct buf *bufq_disksort_get(struct bufq_state *, int); |
102 | |
103 | BUFQ_DEFINE(disksort, 20, bufq_disksort_init); |
104 | |
105 | static void |
106 | bufq_disksort_put(struct bufq_state *bufq, struct buf *bp) |
107 | { |
108 | struct bufq_disksort *disksort = bufq_private(bufq); |
109 | struct buf *bq, *nbq; |
110 | int sortby; |
111 | |
112 | sortby = bufq->bq_flags & BUFQ_SORT_MASK; |
113 | |
114 | bq = TAILQ_FIRST(&disksort->bq_head); |
115 | |
116 | /* |
117 | * If the queue is empty it's easy; we just go on the end. |
118 | */ |
119 | if (bq == NULL) { |
120 | TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq); |
121 | return; |
122 | } |
123 | |
124 | /* |
125 | * If we lie before the currently active request, then we |
126 | * must locate the second request list and add ourselves to it. |
127 | */ |
128 | if (buf_inorder(bp, bq, sortby)) { |
129 | while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { |
130 | /* |
131 | * Check for an ``inversion'' in the normally ascending |
132 | * block numbers, indicating the start of the second |
133 | * request list. |
134 | */ |
135 | if (buf_inorder(nbq, bq, sortby)) { |
136 | /* |
137 | * Search the second request list for the first |
138 | * request at a larger block number. We go |
139 | * after that; if there is no such request, we |
140 | * go at the end. |
141 | */ |
142 | do { |
143 | if (buf_inorder(bp, nbq, sortby)) |
144 | goto insert; |
145 | bq = nbq; |
146 | } while ((nbq = |
147 | TAILQ_NEXT(bq, b_actq)) != NULL); |
148 | goto insert; /* after last */ |
149 | } |
150 | bq = nbq; |
151 | } |
152 | /* |
153 | * No inversions... we will go after the last, and |
154 | * be the first request in the second request list. |
155 | */ |
156 | goto insert; |
157 | } |
158 | /* |
159 | * Request is at/after the current request... |
160 | * sort in the first request list. |
161 | */ |
162 | while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { |
163 | /* |
164 | * We want to go after the current request if there is an |
165 | * inversion after it (i.e. it is the end of the first |
166 | * request list), or if the next request is a larger cylinder |
167 | * than our request. |
168 | */ |
169 | if (buf_inorder(nbq, bq, sortby) || |
170 | buf_inorder(bp, nbq, sortby)) |
171 | goto insert; |
172 | bq = nbq; |
173 | } |
174 | /* |
175 | * Neither a second list nor a larger request... we go at the end of |
176 | * the first list, which is the same as the end of the whole schebang. |
177 | */ |
178 | insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq); |
179 | } |
180 | |
181 | static struct buf * |
182 | bufq_disksort_get(struct bufq_state *bufq, int remove) |
183 | { |
184 | struct bufq_disksort *disksort = bufq->bq_private; |
185 | struct buf *bp; |
186 | |
187 | bp = TAILQ_FIRST(&disksort->bq_head); |
188 | |
189 | if (bp != NULL && remove) |
190 | TAILQ_REMOVE(&disksort->bq_head, bp, b_actq); |
191 | |
192 | return (bp); |
193 | } |
194 | |
195 | static struct buf * |
196 | bufq_disksort_cancel(struct bufq_state *bufq, struct buf *buf) |
197 | { |
198 | struct bufq_disksort *disksort = bufq->bq_private; |
199 | struct buf *bq; |
200 | |
201 | TAILQ_FOREACH(bq, &disksort->bq_head, b_actq) { |
202 | if (bq == buf) { |
203 | TAILQ_REMOVE(&disksort->bq_head, bq, b_actq); |
204 | return buf; |
205 | } |
206 | } |
207 | return NULL; |
208 | } |
209 | |
210 | static void |
211 | bufq_disksort_fini(struct bufq_state *bufq) |
212 | { |
213 | |
214 | KASSERT(bufq->bq_private != NULL); |
215 | kmem_free(bufq->bq_private, sizeof(struct bufq_disksort)); |
216 | } |
217 | |
218 | static void |
219 | bufq_disksort_init(struct bufq_state *bufq) |
220 | { |
221 | struct bufq_disksort *disksort; |
222 | |
223 | disksort = kmem_zalloc(sizeof(*disksort), KM_SLEEP); |
224 | bufq->bq_private = disksort; |
225 | bufq->bq_get = bufq_disksort_get; |
226 | bufq->bq_put = bufq_disksort_put; |
227 | bufq->bq_cancel = bufq_disksort_cancel; |
228 | bufq->bq_fini = bufq_disksort_fini; |
229 | TAILQ_INIT(&disksort->bq_head); |
230 | } |
231 | |
232 | MODULE(MODULE_CLASS_BUFQ, bufq_disksort, NULL); |
233 | |
234 | static int |
235 | bufq_disksort_modcmd(modcmd_t cmd, void *opaque) |
236 | { |
237 | |
238 | switch (cmd) { |
239 | case MODULE_CMD_INIT: |
240 | return bufq_register(&bufq_strat_disksort); |
241 | case MODULE_CMD_FINI: |
242 | return bufq_unregister(&bufq_strat_disksort); |
243 | default: |
244 | return ENOTTY; |
245 | } |
246 | } |
247 | |